There are some literatures and patent applications relating to the researches on using manganese dioxide for desulfurizing fume. For example, CN1824372A discloses the technology of desulfurizing fume with microwave catalysis, which has a higher desulfurizing efficiency for simulation fume, but needs special equipments. Besides, the gas after desulfurization requires to be absorbed with dilute acid, and catalyst beds require regeneration treatment constantly, which are unfavorable to stable operations of production installations for continuous mass industrial production. Chemical manganese dioxide or electrolytic manganese dioxide having very high cost thereof is used in desulfurization treatment in CN 1883764A, so that the production cost is higher and the operations are complex, which is not suitable for actual conditions of China. Besides, the post-treatments of manganese sulfate solution produced by the process of desulfurization are also not mentioned.